Pressure in dysfunctional families builds up (9)

I believe the answer is:

amplifies

'builds up' is the definition.

'pressure in dysfunctional families' is the wordplay.
'pressure' becomes 'p' (abbreviation).
'in' is an insertion indicator.
'dysfunctional' indicates an anagram.
'families' anagrammed gives 'amlifies'.
'p' put into 'amlifies' is 'AMPLIFIES'.

I've seen this clue in The Independent.

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